Genetic analysis of the capsular polysaccharide synthesis locus in 15 Streptococcus suis serotypes

ABSTRACT In a search for the genetic basis for the structural difference between the related Streptococcus pneumoniae capsular serotypes 15B and 15C and for the reported reversible switching between these serotypes, the corresponding capsular polysaccharide synthesis (cps) loci were investigated by keeping in mind that at the structural level, the capsules differ only in O acetylation. The cps locus of a serotype 15B strain was identified, partially PCR amplified with primers based on the related serotype 14 sequence, and sequenced. Sequence analysis revealed, among other open reading frames, an intact open reading frame (designated cps15bM) whose product, at the protein level, exhibited characteristics of previously identified acetyltransferases. Genetic analysis of the corresponding region in a serotype15C strain indicated that the same gene was present but had a premature stop in translation. Closer analysis indicated that the serotype 15B gene contained a short tandem TA repeat consisting of eight TA units. In serotype 15C, this gene contained nine TA units that resulted in a frameshift and a truncated product. Genetic analysis of 17 serotype 15B and 15C clinical isolates revealed a perfect correlation between the serotype and the length of the short tandem repeat in the putative O-acetyltransferase gene. The number of TA repeating units varied between seven and nine in the various isolates. Together, the data strongly suggest that the structural difference between serotypes 15B and 15C is based on variation in the short tandem TA repeat in the O-acetyltransferase gene and that the transition between serotypes is due to slipped-strand mispairing with deletion or insertion of TA units in the cps15bM gene.

Download Full-text

Eight Novel Capsular Polysaccharide Synthesis Gene Loci Identified in Nontypeable Streptococcus suis Isolates

Applied and Environmental Microbiology ◽

10.1128/aem.00315-15 ◽

2015 ◽

Vol 81 (12) ◽

pp. 4111-4119 ◽

Cited By ~ 17

Author(s):

Han Zheng ◽

Shaobo Ji ◽

Zhijie Liu ◽

Ruiting Lan ◽

Ying Huang ◽

...

Keyword(s):

Capsular Polysaccharide ◽

Streptococcus Suis ◽

Diagnostic Tools ◽

Genetic Characteristics ◽

Content Type ◽

Transmission Electron ◽

Polysaccharide Synthesis ◽

Serious Disease ◽

Dependent Pathway ◽

Insight Into

ABSTRACTStreptococcus suisis an important pathogen of pigs and may cause serious disease in humans. Serotyping is one of the important diagnostic tools and is used for the epidemiological study ofS. suis. NontypeableS. suisstrains have been reported in many studies; however, the capsular polysaccharide (CPS) synthesiscpsloci of nontypeable strains have not been analyzed. In this study, we investigated the genetic characteristics ofcpsloci in 78 nontypeable strains isolated from healthy pigs. Eight novelcpsloci (NCLs) were found, and all of them were located between theorfZ-orfXregion and theglfgene. All NCLs possess thewzyandwzxgenes, strongly suggesting that the CPSs of these NCLs were synthesized using the Wzx/Wzy-dependent pathway. Thecpsgenes found in the 78 isolates were assigned to 96 homology groups (HGs), 55 of which were NCL specific. The encapsulation of the 78 isolates was also examined using transmission electron microscopy. Fifty-three isolates were found to have a capsule, and these were of varied thicknesses. Our data enhance our understanding of thecpsgene cluster diversity of nontypeableS. suisstrains and provide insight into the evolution of theS. suiscapsular genes.

Download Full-text

Genotyping and investigating capsular polysaccharide synthesis gene loci of non-serotypeable Streptococcus suis isolated from diseased pigs in Canada

Veterinary Research ◽

10.1186/s13567-017-0417-6 ◽

2017 ◽

Vol 48 (1) ◽

Cited By ~ 17

Author(s):

Han Zheng ◽

Xiaotong Qiu ◽

David Roy ◽

Mariela Segura ◽

Pengchen Du ◽

...

Keyword(s):

Capsular Polysaccharide ◽

Streptococcus Suis ◽

Polysaccharide Synthesis

Download Full-text

Capsular polysaccharide switching in Streptococcus suis modulates host cell interactions and virulence

Scientific Reports ◽

10.1038/s41598-021-85882-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Masatoshi Okura ◽

Jean-Philippe Auger ◽

Tomoyuki Shibahara ◽

Guillaume Goyette-Desjardins ◽

Marie-Rose Van Calsteren ◽

...

Keyword(s):

Host Cell ◽

Capsular Polysaccharide ◽

Inflammatory Mediator ◽

Streptococcus Suis ◽

Cell Interactions ◽

Inflammatory Mediator Production ◽

Composition And Structure ◽

Infection Models ◽

Host Cell Interactions ◽

Blood Dendritic Cell

AbstractThe capsular polysaccharide (CPS) of Streptococcus suis defines various serotypes based on its composition and structure. Though serotype switching has been suggested to occur between S. suis strains, its impact on pathogenicity and virulence remains unknown. Herein, we experimentally generated S. suis serotype-switched mutants from a serotype 2 strain that express the serotype 3, 4, 7, 8, 9, or 14 CPS. The effects of serotype switching were then investigated with regards to classical properties conferred by presence of the serotype 2 CPS, including adhesion to/invasion of epithelial cells, resistance to phagocytosis by macrophages, killing by whole blood, dendritic cell-derived pro-inflammatory mediator production and virulence using mouse and porcine infection models. Results demonstrated that these properties on host cell interactions were differentially modulated depending on the switched serotypes, although some different mutations other than loci of CPS-related genes were found in each the serotype-switched mutant. Among the serotype-switched mutants, the mutant expressing the serotype 8 CPS was hyper-virulent, whereas mutants expressing the serotype 3 or 4 CPSs had reduced virulence. By contrast, switching to serotype 7, 9, or 14 CPSs had little to no effect. These findings suggest that serotype switching can drastically alter S. suis virulence and host cell interactions.

Download Full-text